format json response

*alexandre* has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I'm new to JSON and I want to retrieve the value of a json response attribute here is m code

#!/usr/bin/perl
use warnings;
use Shell;
use JSON;

main();

sub get_balance {
    my $test = libra("account balance f270b16e2fec7a10937d0c32eec34a9b
+2280a7ab8a64e75aa8c84e3583158349");
    print "$test";    
}

sub main {
    get_balance();
}
[download]

it's print : root@vps8279:/usr/lib/cgi-bin# perl libra_test.pl { "balance": 999000000 } what I need is just the result : 999000000 thx

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Re: format json response by haukex (Archbishop) on Oct 29, 2019 at 13:48 UTC
This should work: `my $json = qq/{\n\t"balance": 999000000\n}\n/; my $data = decode_json($json); my $balance = $data->{balance}; print $balance, "\n"; # prints "999000000"` [download] The `decode_json` function is provided by many of the JSON modules, personally I prefer Cpanel::JSON::XS. You can use Data::Dumper or Data::Dump to inspect its return value, and then dereference it accordingly (perlreftut). `use Shell;` Note that Shell is fairly dangerous, as it'll turn any unknown function call into a system command. I assume `libra` is that shell command? You might be interested in my module IPC::Run3::Shell, which is heavily inspired by Shell, but I've added a bunch of features (and, relatively speaking, more safety from common problems). `use IPC::Run3::Shell { chomp=>1 }, qw/ libra /; my $balance = libra(qw/ account balance f270b16e2fec7a10937d0c32eec34a +9b2280a7ab8a64e75aa8c84e3583158349 /);` [download]	[reply] [d/l] [select]
Re: format json response by 1nickt (Canon) on Oct 29, 2019 at 13:55 UTC
Hi welcome to the Monastery. We just saw your buddy doing the Bitcoin app a few months ago! Nice to see y'all are keeping up with the new stuff ;-) I suggest to read the documentation for JSON as well as about Perl data structures (perldsc) so you can access hash elements at will. Also, I suggest getting handy with jq so you can parse random JSON on the commandline. For instance, you could extend your command shown to: `# perl libra_test.pl \| jq .balance` [download] Hope this helps! The way forward always starts with a minimal test.	[reply] [d/l]
Re^2: format json response by alexandre (Scribe) on Oct 29, 2019 at 15:11 UTC
Well thank you so much :-)	[reply]